Turning Point ActivityMaking a turn on a bicycle is easy compared with explaining
what you do to make a bicycle turn. Your position, the bicycle's position,
and the position of the front wheel all make a difference. In our experiments
with bicycles, the Exploratorium staff has discovered that you can initiate
a turn to one side by steering to the other side. Motorcycle riders call
this "counter-steering," a small jerk on the handlebars in one
direction to initiate a turn in the opposite direction.

Try it yourself. Ride your bike in a straight line through
an open area where there is little traffic. When you are moving at a moderate
speed, jerk your handlebars slightly to the right. Notice that your bicycle
and body are thrown to the left, and you have to steer left to remain upright.

When you ride a bike in a straight line, you must make many minor corrections
in order to stay upright. Ron Hipschman, the author of this activity, demonstrates
these corrections by riding along a length of white paper.

The curving tracks show the path of Ron's front wheel as Ron steered his
bike to the left to correct a fall to the left, then to the right to correct
a fall to the right.

You can examine your bicycle's path by riding through a
puddle to wet the tires, then making a sharp left turn. Look at your tracks,
and notice that your front tire swings slightly to the right, then to the
left.

Ask a friend to make a sharp turn and watch his front wheel
and handlebars as he does it. You may notice that he jerks the handlebars
just slightly to the left before he turns right, and vice versa.

At the Exploratorium, our experimentation has convinced
us that you turn your wheel to the right to throw your weight to the left.
To change direction, you need the help of a force outside of yourself and
the bicycle. Trying to change direction without the help of an outside force
is like trying to pull yourself up by your own shoelaces. It doesn't work.
If you were to try to fling yourself to one side, you would go in one direction
and your bike would go in the other, counterbalancing your weight shift.

When you turn your front wheel to the right, your bike
heads to the right, but your body tends to keep going straight. If you are
traveling fast and you twist the wheel sharply, your momentum may cause
you and your bicycle to part company when your bike turns and you continue
in a straight course. If you turn the wheel less sharply, you still feel
the effect of your forward momentum: you feel like you are thrown to the
left. An outside observer, like the one who drew the sketch below, would
see that the push to the left is really just your tendency to continue on
a straight course, interrupted by the turn of the bike's wheel. This push
lets you lean your bike quickly and turn sharply.

Since a bicycle is in a constant state of imbalance, a cyclist can also
start a turn just by taking advantage of the beginning of a fall to one
side and transforming this fall into a leisurely turn.

The Trials bicycle that Libor rides is smaller than most mountain bikes.
This helps him control the bicycle with amazing accuracy. Control is important
since Libor does some of his stunts on ledges of tall buildings. Occasionally
he even jumps between buildings. When watching him perform, the bicycle
appears almost to be an extension of his body.